1. Field of the Invention
This invention relates to anti-inflammatory and analgesic compounds, especially to certain benzofuran and benzothiophene derivatives, pharmaceutical compositions containing them, methods for their use, and methods for preparing these compounds.
2. Background of the Invention
Non-steroidal anti-inflammatory drugs (NSAIDs), have a problem of causing serious side-effects such as gastrointestinal tract distress or nephro-toxicity. NSAIDs inhibit the activity of cyclooxygenase (COX), which is an enzyme involved in prostaglandin G/H synthesis, resulting in the inhibition of the biosynthesis of prostaglandins not only in inflammatory loci but also in stomach and kidney. It has been found that COX exists in two forms: COX-1 and COX-2, Cell, 83, 345, (1995).
COX-1 is expressed in normal cells and controls the function of stomach and kidney, while COX-2 is induced by mitogens or cytokines in inflammatory sites where inflammation and other immunoreactions occur, J. Biol. Chem., 271, 33157(1996).
To avoid the toxicity of NSAIDs due to the inhibition of coexisting COX-1, selective inhibitors of COX-2 have been investigated. The selective COX-2 inhibitors have anti-inflammatory action, pain-relieving action, and/or antipyretic action; with less side effects such as bleeding in the gastrointestinal tract. COX-2 inhibitors may show anticancer activity and lower the induction of asthma in asthmatic patients who are sensitive to conventional NSAIDs. These selective inhibitors of COX-2 may also be used in treating Alzheimer""s disease and osteoporosis of women after menopause.
3. Description of Related Art
U.S. Pat. No. 3,331,854 (American Cyanamid) refers to certain novel furan and thiophene compounds.
U.S. Pat. No. 5,426,113 (Warner Lambert) refers to certain tetrazol-benzothiophene carboxamides in preventing ulcer formation.
U.S. Pat. No. 5,731,342 (Eli Lilly) refers to certain benzothiophenes, which are useful for the treatment of the medical indications associated with post-menopausal syndrome and breast cancer treatment and prevention.
U.S. Pat. Nos. 4,663,347; 4,745,127; 4,822,803; 4,933,351; and 4,621,091 (Merck) refer to certain benzofuran-2-carboxylic acid derivatives as 5-lipoxygenase inhibitors.
U.S. Pat. No.4,621,091 (Merck) refers to certain 3-hydroxybenzothiophene-2-sulfide derivatives as 5-lipoxygenase inhibitors.
DE Pat. No. 3,342,624 (Grote) refers to certain 3-hydroxybenzoyl-benzofuran derivatives.
PCT Published Application No. WO 95/02406 (Warner Lambert) refers to certain use of benzothiophene and benzofuran compounds for monitoring inflammation.
In a first aspect, this invention provides compounds selected from the group of compounds represented by Formula I: 
wherein:
Y is O or S;
A is a xe2x80x94CH2xe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94S(O)xe2x80x94, or xe2x80x94S(O)2xe2x80x94;
Ar is an optionally substituted phenyl;
R1 is hydrogen, alkyl, alkoxy, hydroxy, halo, cyano, xe2x80x94C(O)NR4R5, xe2x80x94COOR4, xe2x80x94NR4R5, wherein R4 and R5 are each independently in each occurrence hydrogen or alkyl;
R2 is hydrogen, alkyl, alkoxy, hydroxy, halo, haloalkyl, nitro, cyano, or xe2x80x94NR4R5, wherein R4 and R5 are as defined previously;
R3 is xe2x80x94SR6, xe2x80x94SOR6, xe2x80x94SO2R6, or xe2x80x94SO2NR4R5 wherein R6 is alkyl, hydroxyalkyl, alkoxyalkyl, carboxyalkyl, or alkoxycarbonylalkyl; and R4 and R5 are as defined previously; or
prodrugs, individual isomers, mixtures of isomers, and pharmaceutically acceptable salts thereof.
In a second aspect, this invention provides pharmaceutical compositions containing a therapeutically effective amount of a compound of Formula I or its pharmaceutically acceptable salt and a pharmaceutically acceptable excipient.
In a third aspect, this invention provides a method of treatment of a disease, in particular an inflammatory and autoimmune disease, in a mammal treatable by administration of a prostaglandin G/H synthase inhibitor, comprising administration of a therapeutically effective amount of a compound of Formula I or its pharmaceutically acceptable salt.
In a fourth aspect, this invention provides processes for preparing compounds of Formula I.
Definitions
Unless otherwise stated, the following terms used in the specification and claims have the meanings given below:
xe2x80x9cAlkylxe2x80x9d means a linear saturated monovalent hydrocarbon radical of one to six carbon atoms or a branched saturated monovalent hydrocarbon radical of three to six carbon atoms, e.g., methyl, ethyl, n-propyl, 2-propyl, tert-butyl, pentyl, and the like.
xe2x80x9cAlkylenexe2x80x9d means a linear saturated divalent hydrocarbon radical of one to six carbon atoms or a branched saturated divalent hydrocarbon radical of three to six carbon atoms, e.g., methylene, ethylene, propylene, 2-methylpropylene, pentylene, and the like.
xe2x80x9cAlkoxyxe2x80x9d, xe2x80x9caryloxyxe2x80x9d, xe2x80x9caralkyloxyxe2x80x9d, or xe2x80x9cheteroaralkyloxyxe2x80x9d means a radical xe2x80x94OR where R is an alkyl, aryl, aralkyl, or heteroaralkyl respectively, as defined herein, e.g., methoxy, phenoxy, benzyloxy, pyridin-2-ylmethyloxy, and the like.
xe2x80x9cAlkoxycarbonylalkylxe2x80x9d means a radical xe2x80x94RaC(O)Rb where Ra is an alkylene group as defined above and Rb is an alkoxy group as defined above e.g., methoxycarbonylethyl, ethoxycarbonylbutyl, and the like.
xe2x80x9cArylxe2x80x9d means a monovalent monocyclic or bicyclic aromatic radical of 6 to 10 ring atoms which is substituted independently with one to five substituents, preferably one, two, or three substituents selected from alkyl, cycloalkyl, cycloalkylalkyl, halo, nitro, cyano, hydroxy, alkoxy, amino, acylamino, alkylamino, dialkylamino, haloalkyl, haloalkoxy, heteroalkyl, xe2x80x94COR (where R is hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl), xe2x80x94(CRxe2x80x2Rxe2x80x3)nxe2x80x94COOR (where n is an integer from 0 to 5, Rxe2x80x2 and Rxe2x80x3 are independently hydrogen or alkyl, and R is hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl) or xe2x80x94(CRxe2x80x2Rxe2x80x3)nxe2x80x94CONRaRb (where n is an integer from 0 to 5, Rxe2x80x2 and Rxe2x80x3 are independently hydrogen or alkyl, and Ra and Rb are, independently of each other, hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl). More specifically the term aryl includes, but is not limited to, phenyl, biphenyl, 1-naphthyl, and 2-naphthyl, and the derivatives thereof.
xe2x80x9cHalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d means the radical fluoro, bromo, chloro, and/or iodo.
xe2x80x9cHaloalkylxe2x80x9d means alkyl substituted with one or more same or different halo atoms, e.g., xe2x80x94CH2Cl, xe2x80x94CF3, xe2x80x94CH2CF3, xe2x80x94CH2CCl3, and the like, and further includes those alkyl groups such as perfluoroalkyl in which all hydrogen atoms are replaced by fluorine atoms.
xe2x80x9cHydroxyalkylxe2x80x9d means an alkyl radical as defined herein, substituted with one or more, preferably one, two or three hydroxy groups, provided that the same carbon atom does not carry more than one hydroxy group. Representative examples include, but are not limited to, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-hydroxymethyl-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 2,3-dihydroxypropyl, 1-hydroxymethyl-2-hydroxyethyl, 2,3-dihydroxybutyl, 3,4-dihydroxybutyl and 2-hydroxymethyl-3-hydroxypropyl, preferably 2-hydroxyethyl, 2,3-dihydroxypropyl and 1-hydroxymethyl-2-hydroxyethyl. Accordingly, as used herein, the term xe2x80x9chydroxyalkylxe2x80x9d is used to define a subset of heteroalkyl groups.
xe2x80x9cOptionally substituted phenylxe2x80x9d means a phenyl ring which is optionally substituted independently with one to four substituents, preferably one or two substituents selected from alkyl, cycloalkyl, cycloalkylalkyl, halo, nitro, cyano, hydroxy, alkoxy, amino, acylamino, monoalkylamino, dialkylamino, haloalkyl, haloalkoxy, heteroalkyl, xe2x80x94COR (where R is hydrogen, alkyl, phenyl or phenylalkyl, xe2x80x94(CRxe2x80x2Rxe2x80x3)nxe2x80x94COOR (where n is an integer from 0 to 5, Rxe2x80x3 and Rxe2x80x2 are independently hydrogen or alkyl, and R is hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl), or xe2x80x94(CRxe2x80x2Rxe2x80x3)n-CONRaRb (where n is an integer from 0 to 5, Rxe2x80x2 and Rxe2x80x3 are independently hydrogen or alkyl, and Ra and Rb are, independently of each other, hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl).
xe2x80x9cLeaving groupxe2x80x9d has the meaning conventionally associated with it in synthetic organic chemistry i.e., an atom or group capable of being displaced by a nucleophile and includes halo (such as chloro, bromo, iodo), alkanesulfonyloxy, arenesulfonyloxy, alkylcarbonyloxy (e.g. acetoxy), arylcarbonyloxy, mesyloxy, tosyloxy, trifluoromethanesulfonyloxy, aryloxy (e.g., 2,4-dinitrophenoxy), methoxy, N,O-dimethylhydroxylamino, and the like.
xe2x80x9cPharmaceutically acceptable excipientxe2x80x9d means an excipient that is useful in preparing a pharmaceutical composition that is generally safe, non-toxic and neither biologically nor otherwise undesirable, and includes an excipient that is acceptable for veterinary use as well as human pharmaceutical use. A xe2x80x9cpharmaceutically acceptable excipientxe2x80x9d as used in the specification and claims includes both one and more than one such excipient.
xe2x80x9cPharmaceutically acceptable saltxe2x80x9d of a compound means a salt that is pharmaceutically acceptable and that possesses the desired pharmacological activity of the parent compound. Such salts include:
(1) acid addition salts, formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like; or formed with organic acids such as acetic acid, propionic acid, hexanoic acid, cyclopentanepropionic acid, glycolic acid, pyruvic acid, lactic acid, malonic acid, succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, 3-(4-hydroxybenzoyl)benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, 1,2-ethane-disulfonic acid, 2-hydroxyethanesulfonic acid, benzenesulfonic acid, 4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-toluenesulfonic acid, camphorsulfonic acid, 4-methylbicyclo[2.2.2]-oct-2-ene-1-carboxylic acid, glucoheptonic acid, 3-phenylpropionic acid, trimethylacetic acid, t-butylacetic acid, lauryl sulfuric acid, gluconic acid, glutamic acid, hydroxynaphthoic acid, salicylic acid, stearic acid, muconic acid, and the like; or
(2) salts formed when an acidic proton present in the parent compound either is replaced by a metal ion, e.g., an alkali metal ion, an alkaline earth ion, or an aluminum ion; or coordinates with an organic base such as ethanolamine, diethanolamine, triethanolamine, tromethamine, N-methylglucamine, and the like.
xe2x80x9cProdrugsxe2x80x9d means any compound which releases an active parent drug, or any compound which changes its oxidation level, according to Formula I in vivo when such prodrug is administered to a mammalian subject. Prodrugs of a compound of Formula I are prepared by modifying functional groups present in the compound of Formula I in such a way that the modifications may be cleaved in vivo to release the parent compound. Prodrugs may also be prepared by incomplete oxidation of certain functional groups, such as sulfur containing functional groups, in such a way that the oxidation of said functional group may be effected in vivo to release a compound according to Formula I. Prodrugs include compounds of Formula I wherein a hydroxy, amino, or sulfhydryl group in a compound of Formula I is bonded to any group that may be cleaved in vivo to regenerate the free hydroxyl, amino, or sulfhydryl group, respectively. Examples of prodrugs include, but are not limited to esters (e.g., acetate, formate, and benzoate derivatives) or carbamates (e.g., N,N-dimethylaminocarbonyl) of hydroxy functional groups and thiol or sulfoxide groups in compounds of Formula I, and the like.
xe2x80x9cProtecting groupxe2x80x9d refers to a grouping of atoms that when attached to a reactive group in a molecule masks, reduces or prevents that reactivity. Examples of protecting groups can be found in T. W. Greene and P. G. Wuts, Protective Groups in Organic Chemistry, (Wiley, 2nd ed. 1991) and Harrison and Harrison et al., Compendium of Svnthetic Organic Methods, Vols. 1-8 (John Wiley and Sons. 1971-1996). Representative amino protecting groups include formyl, acetyl, trifluoroacetyl, benzyl, benzyloxycarbonyl (CBZ), tert-butoxycarbonyl (Boc), trimethylsilyl (TMS), 2-trimethylsilyl-ethanesulfonyl (SES), trityl and substituted trityl groups, allyloxycarbonyl, 9-fluorenylmethyloxycarbonyl (FMOC), nitro-veratryloxycarbonyl (NVOC) and the like. Representative hydroxy protecting groups include those where the hydroxy group is either acylated or alkylated such as benzyl and trityl ethers as well as alkyl ethers, tetrahydropyranyl ethers, trialkylsilyl ethers, and allyl ethers.
xe2x80x9cTreatingxe2x80x9d or xe2x80x9ctreatmentxe2x80x9d of a disease includes:
(1) preventing the disease, i.e. causing the clinical symptoms of the disease not to develop in a mammal that may be exposed to or predisposed to the disease but does not yet experience or display symptoms of the disease,
(2) inhibiting the disease, i.e., arresting or reducing the development of the disease or its clinical symptoms, or
(3) relieving the disease, i.e., causing regression of the disease or its clinical symptoms.
xe2x80x9cA therapeutically effective amountxe2x80x9d means the amount of a compound that, when administered to a mammal for treating a disease, is sufficient to effect such treatment for the disease. The xe2x80x9ctherapeutically effective amountxe2x80x9d will vary depending on the compound, the disease and its severity and the age, weight, etc., of the mammal to be treated.
xe2x80x9cOptionalxe2x80x9d or xe2x80x9coptionallyxe2x80x9d in the above definitions means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not. For example, xe2x80x9cheterocyclo group optionally mono- or di-substituted with an alkyl groupxe2x80x9d means that the alkyl may but need not be present, and the description includes situations where the heterocyclo group is mono- or di-substituted with the s alkyl group and situations where the heterocyclo group is not substituted with the alkyl group.
Compounds that have the same molecular formula but differ in the nature or sequence of bonding of their atoms or the arrangement of their atoms in space are termed xe2x80x9cisomersxe2x80x9d. Isomers that differ in the arrangement of their atoms in space are termed xe2x80x9cstereoisomersxe2x80x9d. Stereoisomers that are not mirror images of one another are termed xe2x80x9cdiastereomersxe2x80x9d and those that are non-superimposable mirror images of each other are termed xe2x80x9cenantiomersxe2x80x9d. When a compound has an asymmetric center, for example, it is bonded to four different groups, a pair of enantiomers is possible. An enantiomer can be characterized by the absolute configuration of its asymmetric center and is described by the R- and S-sequencing rules of Cahn, Ingold and Prelog, (Cahn et al. Angew. Chem. Inter. Edit., 5, 385; (1966) errata 511; Cahn et al. Angew. Chem., 78, 413;(1966) Cahn and Ingold J. Chem. Soc. (London), 612; (1951) Cahn et al. Experientia, 12, 81;(1956), Cahn, J. Chem.Educ., 41, 116, (1964)) or by the manner in which the molecule rotates the plane of polarized light and designated as dextrorotatory or levorotatory (i.e., as (+) or (xe2x88x92)-isomers respectively). A chiral compound can exist as either individual enantiomer or as a mixture thereof. A mixture containing equal proportions of the enantiomers is called a xe2x80x9cracemic mixturexe2x80x9d.
The compounds of this invention may exist in stereoisomeric form if they possess one or more asymmetric centers or a double bond with asymmetric substitution and, therefore, can be produced as individual stereoisomers or as mixtures. Unless otherwise indicated, the description is intended to include individual stereoisomers as well as mixtures. The methods for the determination of stereochemistry and the separation of stereoisomers are well-known in the art (see discussion in Chapter 4 of xe2x80x9cAdvanced Organic Chemistryxe2x80x9d, 4th edition J. March, John Wiley and Sons, New York, 1992).
Throughout the application the following abbreviations are used with the following meanings:
Nomenclature
The naming and numbering of the compounds of this invention is illustrated below. 
In general, the nomenclature used in this Application is based on AUTONOM(trademark) v.4.0, a Beilstein Institute computerized system for the generation of IUPAC systematic nomenclature.
Representative Compounds of this Invention are as Follows:
Compound of Formula I wherein R1, R2, R3, Y, A, and Ar are as defined below:
Preferred Embodiments
While the broadest definition of this invention is set forth in the Summary of the Invention, certain compounds of Formula I are preferred.
In certain preferred embodiments Ar is a phenyl optionally substituted at one or more postions, preferably with one to two substitutents independently selected from the group consisting of halo and alkoxy, and R3 is xe2x80x94SO2R6, wherein R6 is alkyl.
In another embodiment, another preferred group of compounds is that wherein Ar is phenyl optionally substituted at one or more positions, preferably with one to two sybstitutents independently selected from the group consisting of halo and alkoxy; R3 is xe2x80x94SO2R6, wherein R6 is alkyl; Y is xe2x80x94Oxe2x80x94; and A is xe2x80x94Sxe2x80x94; and yet a more preferred group of compounds is that wherein Ar is phenyl optionally substituted at one or more positions, preferably with one to two substitutents independently selected from the group consisting of halo and alkoxy; R3 is xe2x80x94SO2R6, wherein R6 is alkyl; Y is O; A is S; and R1 is alkyl or cyano.
In another embodiment another preferred group of compounds is that wherein Ar is phenyl optionally substituted at one or more positions, preferably with one to two substitutents independently selected from the group consisting of halo and alkoxy; R3 is xe2x80x94SO2R6; wherein R6 is alkyl; Y is xe2x80x94Sxe2x80x94; and A is xe2x80x94Sxe2x80x94; and yet a more preferred group of compounds is that wherein Ar is phenyl optionally substituted at one or more positions preferably with one to two substitutents independently selected from the group consisting of halo and alkoxy; R3 is xe2x80x94SO2R6, wherein R6 is alkyl; Y is S; A is S; and R1 is alkyl or cyano.
Within the foregoing preferred embodiment another preferred group of compounds is that wherein Ar is phenyl optionally substituted at one or more positions, preferably with one to two substitutents independently selected from the group consisting of halo and alkoxy; R3 is xe2x80x94SO2R6, wherein R6 is alkyl; Y is xe2x80x94Sxe2x80x94; and A is xe2x80x94Oxe2x80x94; and yet a more preferred group of compounds is that wherein Ar is phenyl optionally substituted at one or more positions, preferably with one to two substitutents independently selected from the group consisting of halo and alkoxy; R3 is xe2x80x94SO2R6, wherein R6 is alkyl; Y is S; A is O; and R1 is alkyl or cyano.
While the broadest definition of the invention is set forth in the Summary of the Invention, certain compounds of Formula I are preferred. For example, preferred compounds of Formula I are those in which R1 is cyano or alkyl, R2 is hydrogen or alkyl, R3 is alkylsulfonyl, A is xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94, Y is xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94, and Ar is unsubstituted, monosubstituted, or disubstituted phenyl. Even more preferred compounds of Formula I are those in which A is xe2x80x94Sxe2x80x94or xe2x80x94Oxe2x80x94, Y is xe2x80x94Sxe2x80x94, R1 is cyano, R2 is hydrogen, R3 is alkylsulfonyl, and Ar is a phenyl mono or disubstituted with halo or alkoxy.
General Synthetic Scheme
Compounds of this invention can be made by the methods depicted in the reaction schemes shown below.
The starting materials and reagents used in preparing these compounds are either available from commercial suppliers such as Aldrich Chemical Co., (Milwaukee, Wis.), Bachem (Torrance, Calif.), or Sigma (St. Louis, Mo.) or are prepared by methods known to those skilled in the art following procedures set forth in references such as Fieser and Fieser""s Reagents for Organic Synthesis, Volumes 1-17 (John Wiley and Sons, 1991); Rodd""s Chemistry of Carbon Compounds, Volumes 1-5 and Supplementals (Elsevier Science Publishers, 1989); Organic Reactions, Volumes 1-40 (John Wiley and Sons, 1991), March""s Advanced Organic Chemistry, (John Wiley and Sons, 4th Edition) and Larock""s Comprehensive Organic Transformations (VCH Publishers Inc., 1989). These schemes are merely illustrative of some methods by which the compounds of this invention can be synthesized, and various modifications to these schemes can be made and will be suggested to one skilled in the art having referred to this disclosure.
The starting materials and the intermediates of the reaction may be isolated and purified if desired using conventional techniques, including but not limited to filtration, distillation, crystallization, chromatography, and the like. Such materials may be characterized using conventional means, including physical constants and spectral data.
Unless specified to the contrary, the reactions described herein take place at atmospheric pressure over a temperature range from about xe2x88x9278xc2x0 C. to about 150xc2x0 C., more preferably from about 0xc2x0 C. to about 125xc2x0 C. and most preferably at about room (or ambient) temperature, e.g., about 20xc2x0 C.
A person of ordinary skill in the art will have no difficulty, having regard to that skill and this disclosure, in determining how to synthesize compounds of this invention.
Schemes A, and B, describe methods to prepare the compounds of Formula I. 
Scheme A describes the synthesis of a compound of Formula I wherein A is xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94; Y is xe2x80x94Sxe2x80x94; R and Rxe2x80x2 are alkyl; R1 is cyano; n is one or two, R2, R3 and Ar are as defined in the Summary of the Invention.
In Step 1, a certain aldehyde of Formula 1, wherein R is alkyl, preferably wherein R is methyl, can be protected by treatment with an alcohol such as methyl alcohol, in the presence of an acid catalyst such as p-TsOH, to give an acetal of Formula 2, preferably 1-(1,1-dimethoxy-methyl)-4-methylsulfanyl-benzene. In general, the compounds of Formula 1 are commercially available or can be readily synthesized by those of ordinary skill in the art ,see e.g., Watabe, et al, J.Chem.Soc.Chem.Commun.; 10; 1983; 585-586.
In Step 2, the xe2x80x94SR group of a certain compound of Formula 2 wherein R and Rxe2x80x2 are alkyl, preferably wherein R and Rxe2x80x2 are methyl, can be oxidized with MCPBA, OXONE(trademark), and the like to provide a sulfoxide or sulfone of Formula 3, wherein R and Rxe2x80x2 are alkyl, preferably R and Rxe2x80x2 are methyl. Suitable solvents for the reaction are alcohols (such as methanol and ethanol) or halogenated solvents (such as dichloromethane, chloroform and the like). Sulfoxides of Formula 3 may be similarly converted to the corresponding sulfones. It is appreciated that this second oxidation may be performed at various points in Scheme A as may be required by the skilled artisan.
In Step 3, a certain acetal of Formula 3, wherein R and Rxe2x80x2 are alkyl, preferably wherein R and Rxe2x80x2 are methyl, can be hydrolyzed with a suitable amount of acid, such as diluted hydrochloric acid or sulfuric acid in a suitable inert solvent such as THF, to give an aldehyde of Formula 4, wherein R is alkyl, preferably wherein R is methyl.
In Step 4, a certain aldehyde of Formula 4, wherein R is alkyl, preferably wherein R is methyl, can be condensed with malonic acid in the presence of pyridine or an alkoxide as a catalyst, preferably pyridine to give a 3-(4-alkylsulfonyl-phenyl)-acrylic acid of Formula 5, wherein R is alkyl, preferably wherein R is methyl, according to the method of Wiley, R. H.; Smith, N. R. Org. Synth. Coll. Vol IV, 731-734. Suitable solvents are inert solvents such as THF and the like.
In Step 5, a certain intermediate acid chloride of Formula 6, wherein R is alkyl, preferably wherein R is methyl, can be prepared according to the method of Connor, D. T., et al. J. Med. Chem. 1992, 35, 958-65; wherein the acrylic acid of Formula 5, wherein R is alkyl, preferably wherein R is methyl, can then be converted to the benzothiophene of Formula 6, wherein R is alkyl, preferably wherein R is methyl, by treatment with SOCl2 in the presence of pyridine in suitable solvents such as polar aprotic solvents, e.g. DMF, DMSO, chlorobenzene and the like.
In Step 6, a certain acid chloride of Formula 6, wherein R is alkyl, preferably wherein R is methyl, can be amino-de-halogenated with ammonia in THF or an halogenated solvent such as dichloromethane, chloroform, and the like, to give a certain amide of Formula 7, wherein R is alkyl, preferably wherein R is methyl.
In Step 7, a certain amide of Formula 7, wherein R is alkyl, preferably wherein R is methyl, can be dehydrated preferably in the presence of an anhydride such as trifluoroacetic anhydride, trifluoromethanesulfonic anhydride, and the like in an halogenated solvent, such as dichloromethane, chloroform, and the like to give the nitrile of Formula 8, wherein R is alkyl, preferably wherein R is methyl.
In Step 8, a nucleophilic displacement of the chlorine atom of a certain compound of Formula 8, wherein R is alkyl, preferably wherein R is methyl, by a certain phenol or thiophenol of Formula Arxe2x80x94AH wherein A is xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94, in the presence of a base such as potassium hydroxide, potassium hexamethyldisilazide and the like, in an inert solvent such as DMF can give the 3-substituted-2-cyano-6-alkylsulfoxy-benzothiophene of Formula I, wherein R is alkyl, preferably wherein R is methyl.
Scheme B describes the synthesis of a compound of Formula I wherein A is xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94, Y is xe2x80x94Oxe2x80x94, R1 is cyano, R2, R3 and Ar are as defined in the Summary of the Invention. Within this scheme the groups R, Rxe2x80x2 and Rxe2x80x3 are each independently of each other preferably alkyl groups. 
In Step 1, a certain acid of Formula 9 can be esterified by conditions well known in the art, i.e. with an alcohol under acidic conditions. Subsequently the xe2x80x94SR group can be oxidized with MCPBA, OXONE(trademark), and the like to provide a sulfoxide or sulfone of Formula 10. Sulfoxides of Formula 10 may be similarly converted to the corresponding sulfones. It is appreciated that this second oxidation may be performed at various points in Scheme B as may be required by the skilled artisan.
Suitable solvents are alcohols such as methanol or ethanol or halogenated solvents such as dichloromethane, chloroform, and the like.
In Step 2, the ether and ester groups of a certain compound of Formula 10 can be hydrolyzed with acid reagents such as pyridinium hydrochoride, boron trichloride, hydrobromic acid, and the like, preferably pyridinium hydrochloride, and the acid group can be further esterified by conditions well known in the art to give a compound of Formula 11.
In Step 3, the phenol group of a certain compound of Formula 11 can be alkylated with chloroacetonitrile under basic conditions, in a suitable inert solvent such as DMF, DMSO, benzene, toluene, and the like. A suitable base can be sodium carbonate, potassium carbonate, triethylamine, and the like.
In Step 4, a certain compound of Formula 13 can be obtained by internal cyclization to form a benzofuran ring. Such cyclization can be effected with potassium tert-butoxide in an inert solvent such as toluene.
In Step 5, the hydroxyl group of a certain compound of Formula 13 can be protected by mesylation with methane sulfonyl chloride under basic conditions to provide a certain compound of Formula 14.
In Step 6, a nucleophilic displacement of the mesylate group of a certain compound of Formula 14 by a certain optionally substituted benzenethiol of Formula Arxe2x80x94AH in the presence of sodium hydride in an inert solvent or a mixture of solvents such as THF or DMF, can give a compound of Formula I, wherein A is S or O, and Y is O.
General Utility
The compounds of the invention are inhibitors of prostaglandin G/H Synthase I and II (COX I and COX II), especially COX II, in vitro, and as such are expected to possess both anti-inflammatory and analgesic properties in vivo. See, for example, Goodman and Gilmans""s xe2x80x9cThe Pharmacological Basis of Therapeuticsxe2x80x9d, Ninth Edition, McGraw Hill, New York, 1996, Chapter 27. The compounds and compositions containing them are therefore useful as anti-inflammatory and analgesic agents in mammals, especially humans. They find utility in the treatment of fever, inflammation, and pain caused by conditions such as rheumatic fever, symptoms associated with influenza or other viral infections, low back and neck pain, dysmenorrhoea, headache, dental pain, sprains, strains, sports injuries, bursitis, tendonitis, myositis, synovitis, arthritis (rheumatoid arthritis and osteoarthritis), gout, ankylosing spondylitis, burns, or injuries. They may be used to inhibit prostanoid-induced smooth muscle contractions (e.g., in the treatment of dysmenorrhoea, premature labor, and asthma) and to treat autoimmune disorders (such as systemic lupus erythematosus and type I diabetes).
As inhibitors of prostaglandin G/H Synthase, the compounds of this invention are also expected to be useful in the prevention and treatment of cancer, in particular colon cancer. It has been shown that COX-2 gene expression is upregulated in human colorectal cancers and that drugs that inhibit prostaglandin G/H Synthase are effective in animal models of cancer (Eberhart, C. E., et. al., Gastroenterology, 107, 1183-1188, (1994), and Ara, G. and Teicher, B. A., Prostaglandins, Leukotrienes and Essential Fatty Acids, 54, 3-16, (1996)). In addition, there is epidemiological evidence that shows a correlation between use of drugs that inhibit prostaglandin G/H synthase and a reduced risk of developing colorectal cancer (Heath, C. W. Jr., et. al., Cancer, 74, No. 10, 2885-8, (1994)).
The compounds of this invention are also expected to be useful in the prevention and treatment of Alzheimer""s disease. Indomethacin, an inhibitor of prostaglandin G/H synthase, has been shown to inhibit the cognitive decline of Alzheimer""s patients (Rogers, J., et. al., Neurology, 43, 1609, (1993)). Also, the use of drugs which inhibit prostaglandin G/H synthase has been linked epidemiologically with a delayed onset of Alzheimer""s disease (Breitner, J. C. S., et. al., Neurobiology of Aging, 16, No. 4, 523, (1995) and Neurology, 44, 2073, (1994)).
Testing
The anti-inflammatory activity of the compounds of this invention may be assayed by measuring the ability of the compound to inhibit COX I and COX II, especially COX II, in vitro, using a radiometric assay, as described in more detail in Example 4. It may also be assayed by in vivo assays such as the Rat Carrageenan Paw and Rat Air-Pouch assays, as described in more detail in Examples 5 and 6. The analgesic activity of the compounds of this invention may be assayed by in vivo assays such as the Randall-Selitto assay and the rat arthritis pain model, as described in Example 7.
Administration and Pharmaceutical Composition
In general, the compounds of this invention will be administered in a therapeutically effective amount by any of the accepted modes of administration for agents that serve similar utilities. The actual amount of the compound of this invention, i.e., the active ingredient, will depend upon numerous factors such as the severity of the disease to be treated, the age and relative health of the subject, the potency of the compound used, the route and form of administration, and other factors.
Therapeutically effective amounts of compounds of Formula I may range from approximately 0.005-10 mg per kilogram body weight of the recipient per day, preferably about 0.05-1 mg/kg/day. Thus, for administration to a 70 kg person, the dosage range would preferably be about 3.5 mg to 400 mg per day.
In general, compounds of this invention will be administered as pharmaceutical compositions by any one of the following routes: oral, systemic (e.g., transdermal, intranasal or by suppository), or parenteral (e.g., intramuscular, intravenous or subcutaneous) administration. The preferred manner of administration is oral using a convenient daily dosage regimen, which can be adjusted according to the degree of affliction. Compositions can take the form of tablets, pills, capsules, semisolids, powders, sustained release formulations, solutions, suspensions, elixirs, aerosols, or any other appropriate compositions.
The choice of formulation depends on various factors such as the mode of drug administration (e.g., for oral administration, formulations in the form of tablets, pills or capsules are preferred) and the bioavailability of the drug substance. Recently, pharmaceutical formulations have been developed especially for drugs that show poor bioavailability based upon the principle that bioavailability can be increased by increasing the surface area i.e., decreasing particle size. For example, U.S. Pat. No. 4,107,288 describes a pharmaceutical formulation having particles in the size range from 10 to 1,000 nm in which the active material is supported on a crosslinked matrix of macromolecules. U.S. Pat. No. 5,145,684 describes the production of a pharmaceutical formulation in which the drug substance is pulverized to nanoparticles (average particle size of 400 nm) in the presence of a surface modifier and then dispersed in a liquid medium to give a pharmaceutical formulation that exhibits remarkably high bioavailability.
The compositions are comprised of, in general, a compound of Formula I in combination with at least one pharmaceutically acceptable excipient. Acceptable excipients are non-toxic, aid administration, and do not adversely affect the therapeutic benefit of the compound of Formula I. Such excipient may be any solid, liquid, semi-solid or, in the case of an aerosol composition, gaseous excipient that is generally available to one of skill in the art.
Solid pharmaceutical excipients include starch, cellulose, talc, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, magnesium stearate, sodium stearate, glycerol monostearate, sodium chloride, dried skim milk, and the like. Liquid and semisolid excipients may be selected from glycerol, propylene glycol, water, ethanol, and various oils, including those of petroleum, animal, vegetable or synthetic origin, e.g., peanut oil, soybean oil, mineral oil, sesame oil. Preferred liquid carriers, particularly for injectable solutions, include water, saline, aqueous dextrose, and glycols.
Compressed gases may be used to disperse a compound of this invention in aerosol form. Inert gases suitable for this purpose are nitrogen, carbon dioxide, etc.
Other suitable pharmaceutical excipients and their formulations are described in Remington""s Pharmaceutical Sciences, edited by E. W. Martin (Mack Publishing Company, 18th ed., 1990).
The level of the compound in a formulation can vary within the full range employed by those skilled in the art. Typically, the formulation will contain, on a weight percent (wt %) basis, from about 0.01-99.99 wt % of a compound of Formula I based on the total formulation, with the balance being one or more suitable pharmaceutical excipients. Preferably, the compound is present at a level of about 1-80 wt %. Representative pharmaceutical formulations containing a compound of Formula I are described in Example 3.